Berlin 2012 – wissenschaftliches Programm
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DS: Fachverband Dünne Schichten
DS 33: Thermoelectric materials II: Reduced dimensionality (Focused session – Organizers: Meyer, Heiliger)
DS 33.5: Vortrag
Donnerstag, 29. März 2012, 12:30–12:45, H 2032
Thermoelectric power factor of a 70 nm Ni-nanowire in a magnetic field — •Rüdiger Mitdank1, Martin Handwerg1, Corinna Steinweg2, William Töllner3, Mihaela Daub4, Kornelius Nielsch3, and Saskia F. Fischer1 — 1Novel Materials, Institut für Physik, Humboldt Universität zu Berlin, Newtonstr. 15, 12489 Berlin, Germany — 2Werkstoffe und Nanoelektronik, Ruhr-Universität Bochum, 44780 Bochum, Germany — 3Institute of Applied Physics, Universität Hamburg, Jungiusstr. 11, 20355 Hamburg, Germany — 4Max Planck Institute of Microstructure Physics, Weinberg 2, 06120, Germany.
Thermoelectric (TE) properties of a single nanowire (NW) are investigated in a microlab which allows the determination of the Seebeck coefficient S and the conductivity σ [1]. A significiant influence of the magnetization of a 70 nm ferromagnetic Ni-NW on its power factor S*σ is observed. Mainly, an evident relationship between magnetoresistance and magneto-thermopower was found, confirming Mott's relation. We detected a strong magneto-thermopower effect of about 10% and an anisotropic magneto resistance as a function of an external magnetic field B in the order of 1%. At B = 0 T we determined the absolute value of S = - (19 +- 2) μV/K. At zero field the figure of merit ZT = 0.02 was calculated using the Wiedemann-Franz- law for the thermal conductivity. The TE efficiency increases in a transversal magnetic field (B =0.5 T) due to an enhanced power factor by nearly 20%.
[1] http://arxiv.org/abs/1111.1873